The present invention relates to a display device and, in particular, relates to a liquid crystal display device in which measures against display unevenness caused by generation of a region where no alignment film is formed in a case where the screen resolution is increased.
A liquid crystal display device has a configuration in which a TFT substrate, on which pixels each including a pixel electrode, a thin film transistor (TFT), and the like are formed in a matrix and a counter substrate opposed to the TFT substrate are arranged with a liquid crystal sandwiched between the TFT substrate and the counter substrate. A transmittance of light by liquid crystal molecules is controlled on a pixel-by-pixel basis, to form an image.
In the liquid crystal display device, alignment films are respectively formed on the TFT substrate and the counter substrate to cause initial alignment of the liquid crystal molecules. On the TFT substrate side, unevenness can easily occur because various elements, e.g., contact holes and the pixel electrodes, are formed. In particular, a contact hole allowing a source electrode of the TFT to be electrically conductive to a corresponding pixel electrode has a large diameter, and therefore largely affects the uniformity of application of the alignment film.
Japanese Unexamined Patent Application Publication No. 2002-289864 describes a configuration in which a tapered shape of a contact hole is changed in three levels to prevent occurrence a void at the bottom of the contact hole, thereby eliminating a failure of electrical continuity in the contact hole. Japanese Unexamined Patent Application Publication No. 2010-072457 describes a configuration in which an angle of a wall surface of a contact hole is made small so that a failure of electrical continuity in the contact hole is prevented. Japanese Unexamined Patent Application Publication No. Hei11 (1999)-183929 describes a configuration in which a radius of curvature of an upper cross section of a contact hole is defined to prevent a failure of electrical continuity in the contact hole.